The present invention relates to a machine for the mass-centering of rotors.
Machines which serve the purpose of mass-centering function so that during the mass-centering process the shaft axis of the rotor is made to coincide with the principal axis of inertia or mass axis. Alternatively, the rotor axis is shifted into an axis favorable for balancing. This method is especially used for crankshafts because the methods for unbalance correction are limited. Generally, only counter weights can be used for correction. Also, the counter weights representing predetermined compensations for the mass forces that act on the crankshaft should remain unaltered, if possible.
In a previously known design of a mass-centering machine, such as described in German Patent 975086, the raw crankshaft is received by a balancing cage which is spring supported with respect to the bed of the machine and has rotational and vibrational freedom. Drilling spindles for applying machining centers are located inside each of the two journals of the cage. The cage has two adapter plates interconnected by longitudinal beams. The cage is balanced but becomes unbalanced when the raw crankshaft forging is inserted. Such unbalance is eliminated by shifting the shaft inside the rotating cage. This machine is unable to accept raw crankshafts of different length, and at best, minor differences in crankshaft length can only be accommodated through the adapter and ajustment devices on the adapter discs.
From the printed publication "Die Automobil Industrie und Schenck" (Pamphlet B 1112 - 20 478 A, Carl Schenck AG, Darmstadt) a machine of the above type for mass-centering of rotors in the form of raw crankshafts has two headstocks supported by the bed of the machine through springs bolted to the headstock and machine bed. The headstocks have approximately square dimensions as viewed in the longitudinal direction of the machine and are connected to each other by means of four beams and clamping devices provided on the corners of the square. Within the space defined by the beams adapter discs are provided which are synchronously turnable and rotatably supported with respect to the headstocks. Clamping pieces and counter supports are provided on the side of the adapter discs pointing away from the headstock. The clamping pieces and counter supports between which the end journals of the crankshaft may be placed may be actuated by adjustment drives. By means of two adjustment drives per adapter disc, it is possible to shift each crankshaft end out of the axis of rotation of the adapter discs in two different directions. For example, the crankshaft axis may then be made to coincide with the principal axis of inertia. The device for applying the machining centers is separately placed on the bed of the machine.
The machine of the above publication is not well suited for speedy adjustment of rotors of different length. Such rapid adjustment is needed within the framework of flexible manufacturing, because for each adjustment a multiplicity of connections must be loosened between the machine components. The headstocks and the device that apply the machining centers must also be separately locked in addition to being shifted.